Oscillation generator



March 28, 1950 H. A. WHEELER oscILLATIoN GE1\1ERAT0Ry Filed July l15,1947 INVENTOR HAROLD A. WHEELER llllllj UM/lfm Patented Mar. 28, 1950OSCILLATION GENERATOR Harold A. Wheeler, Great Neck, N. Y., assignor toHazeltine Research, Inc., Chicago, Ill., a corporation of IllinoisApplication July 15, 1947, Serial No. 761,113

(Cl. Z50-36) 15 Claims. l

This invention relates to oscillation generators and, particularly, tooscillation generators adapted for operation at any frequency within arelatively wide range of frequencies.

Many conventional oscillation generators employ resistor-condenserself-bias networks in the input circuits thereof. Besides permittingsuch an oscillation generator to be self-starting, the input-circuitresistor-condenser network has developed across its condenser aunidirectional potential which acts as a control electrode-cathode biasfor the oscillator tube. This bias tends to produce stable oscillationin a manner which may briey be described as follows, it being initiallyassumed that the generator is generating oscillations of uniformlyconstant amplitude and is supplying oscillatory energy to a load device.If the amplitude of oscillation tends to increase due to a change in theload or other operating condition, the above-mentioned bias increases todecrease the interval of anode-current ow during each oscillation cycleand thereby tends to maintain the amplitude of oscillation substantiallyunchanged or at an equilibrium value. Conversely, if the amplitude ofoscillation tends to decrease as a result of a change in some operatingcondition, the bias decreases to increase the interval of anode-currentflow and thereby again tends to maintain the amplitude of oscillationsubstantially constant at the above-mentioned equilibrium value.

This stabilizing or regulating action in oscillation generatorsheretofore proposed prevails only when the time constant of theresistor-condenser network is smaller than the well-known time constantof damping of the frequency-determining circuit of the oscillationgenerator. Such oscillation generatorsmay readily be built to performsatisfactorily at a single frequency or over a rela-` tively narrowrange of frequencies. Considerable diiliculty is encountered, however,in constructing prior oscillation generators of the type underconsideration for stable operation at any frequency within acomparatively wide range of frequencies. One reason for this is that thexed time constant of the resistor-condenserA network in the inputcircuit of the oscillator cannot be designed to effect the mostfavorable operation over the entire wide range of frequencies. Forexample, a resistor-condenser network having a large time constant isnecessary for satisfactory operation over a low-frequency portion of thefrequency range of the generator in order that the network may maintainthe control electrodecathode bias of the oscillator tube suiiciently isto be operated at any given time.

constant throughout each of the relatively long operating cycles. At thehigher operating frequencies of a relatively wide frequency range,however, this large time constant of the network proves to be so largethat the control electrodecathode bias potential is unable to readjustitself sufficiently fast to follow variations of the amplitude ofoscillations resulting from changes in operating conditions.Consequently, an overload condition may reduce the feed-back excitationsupplied from the output circuit to the input circuit of the oscillationgenerator to such an extent that the excitation voltage no longerexceeds the bias potential. This condition may prevail for a period ofmany cycles so that the oscillation generator ceases to operate orblocks. When the bias potential provided by the charge on the networkcondenser decays to a value less than the excitation potential, theoscillation generator r-esumes operation. It soon thereafter ceases tooscillate again for the reasons stated above, thus causing intermittentoperation at an audio-frequency or radio-frequency rate or which mayexist in more pronounced form often called blocking. For stableoperation at the higher operating frequencies, therefore, the inputcircuit of heretofore proposed oscillation generators should have a timeconstant which is much smaller than normally provided for low-frequencyoperation. An oscillation generator of the lastmentioned type with aninput circuit having asmall time constant would not provide good fre;quency stability in the low-frequency portion ofv its operating rangedue to an undesirable phaseI shift introduced by the time-constantAcircuit; This phase shift, by alteringthe desired re'; lation betweenthe input and output circuit volte' ages, would cause frequencyinstability in the aforesaid portion of the operating range.

It will be seen, therefore, that the resistor# condenser network used inthe input circuit of a." conventional oscillation generator should havelfor best operation widely different time constantsl depending upon theparticular portion of the wide range of frequencies in which thegenerator A compromise value for the input-circuit time constant mayundesirably result in a faulty operation or a complete lack of operationin some portion of the aforesaid wide rang-e so that such an expedientis impractical when operation at any frequency within a wide range offrequencies is required.

For some high-frequency applications, it is desirable to employ in theinput circuitof an oscillation generator a resistor-condenser networkincluding a condenser having a relatively large value of capacitance anda resistor having a large resistance value. The network then has, ofcourse, a correspondingly large time constant. A controlelectrode-cathode resistor having a large value of resistance may berequired, for example, to avoid unnecessarily loading the generatortuned circuit which is coupled in circuit with the resistor-condensernetwork. This re-4 quirement, together with that of stabilized operationover a very wide frequency range,- therefore presents a difcult problem.In addition to the foregoing requirements, it may also be desirable forsome applications that the oscillator maintain its amplitude ofoscillation substantially constant at any frequency within a relativelywide range of frequencies. In practice these several requirements areynot easy to achieve.

It'is an object of the present invention, therefore, to provide a newand improved oscillation generator whch avoids one or more of theabovementioned disadvantages and limitationsof prior such generators.

It is another object-of the invention to provide a new and improvedoscillation generator adapted to have high operating stability at anyfrequency within a Wide range of frequencies and onewhich tolerates theuse of an input-circuit resistor-condenser self-bias network having alarge time constant.

It is a further object of the invention to provide a new and improvedoscillation generator which has a substantially reduced tendency toexhibit intermittent operation over at least a major portion of arelatively wide range of operating frequencies.

y'It isyet another object of the-invention to provide a new and improvedoscillaticn generator which not only has a reduced tendency to generateintermittent oscillations atany frequency within a relatively Wide rangeof operating frequencies butalso is one which maintains the oscillationamplitude substantially constant over the entire range.

In accordance with aparticular form of the invention, an oscillationgenerator adapted for operation at any frequency within a relativelywide range of frequencies comprises an oscillatory circuit having apredetermined time constant of damping and means, including aconductancecontrolling circuit, coupled to the oscillatory circuit forgenerating oscillations therein. The conductance-controlling circuitincludes an energystorage impedance network having a .time constantlonger than the aforesaid tme constant of damping so that the generationof oscillations tends to be intermittent at frequencies within at leastaportion of the above-mentioned relatively Wide range of frequencies.vThe oscillation generator also includes an energizing circuit for theaforesaid means including energy-limiting and energy-storage impedancemeans providing with the first-mentioned means a time constant shorterthan the time constant ofY damping, substantially to reduce the tendencyof the oscillation generation to be intermittent over the aforesaidportion of said frequency range.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawing, and itsscope will be pointed out in the appended claims.

Referring now to the drawing, Fig. 1 is a circuit .wave-signal receiverof somewhat conventional design which utilizes an oscillation generatorembodying one form of the present invention. In general, the receiverincludes a radio-fre- 4quency amplifier Iof one or more stages having aninput circuit coupled to an antenna system II, I2 and having an outputcircuit coupled to a modulator I3. "The modulator I3 comprises a unitof:Y a Afrequency converter which includes an oscillation generator I4,more fully to be described hereinafter. Coupled in cascade with themodulator I3 in the order named are an intermediate-frequency ampliferI5 of one or vmore stages, a frequency detector I6, an audio-frequencyamplifier I'I and a sound-reproducing device I8. Anautomatic-amplification-control or A. V. C. output circuit of thefrequency detector IB is coupled to the input circuit of one or more ofthe tubes of the radio-frequency amplifier I0, the modulator I3, and theintermedfate-frequency amplifier I5 in order to maintain the amplitudeof the signal input to the frequency detector I6 within a relativelynarrow range for a relatively wide range of received signal intensities.

It will be understood that the various units just described may, withthe exception 0f the 0scillation. generator I4, be of conventionalconstruction and operation, .the details of which are well known in theart so that further detailed description thereof is unnecessary.

Considering briefly the operation of the receiver as a whole, butneglecting for the moment the detailed operation of the oscillationgenerator I4 presently to be described, a desired frequencymodulatedwave signal is intercepted by the antenna system II, I2, selected andamplified by the radio-frequencyamplier I0, and converted by thefrequency converter including the units I3 and I4 to afrequency-modulated intermediatefrequency wave signal which is amplifiedby the intermediate-frequency amplifier I5. The output signal of thelatter is applied to the frequency detector I6 which derives theaudio-frequency modulation components of the received wave signal. Theseaudio-frequency components are, in turn, amplifledin the audio-frequencyamplifier I'I and are reproduced by the signal-reproducing device I8 ina conventional manner. The automatic-amplification-control or A.,V. C.vbias derived by the frequency detector I6 is effective to control theamplification of one or more of the units I0, I3, and I5 to maintain theintensity of the signal input to the frequency detector I 6 within arelatively narrow range for a Wide range of received signal intensities.

Referring now more particularly to the portion of the receiver embodyingthe present invention, the oscillation generator I4 there represented isadapted for operation at any frequency within a relatively wide range offrequencies and comprises an oscillatory circuit 20 having apredetermined time constant of damping. This time constant is.determined by the losses in the oscillatory circuit as is well known inthe art. The oscillatory circuit 20 comprises a parallel-resonantcircuit including an adjustable inductor 2I,the

inductance value of which may be conventionally controlled by aferromagnetic core, and a variable condenser 22. The inductor 2I, whichis inductively coupled to an input circuit of the modulator I 3, isadjustable to adjust the resonant frequency of the oscillatory circuit20 and, accordingly, is unicontrolled as indicated by the broken line 23with one or more similar tuning elements in the radio-frequencyamplifier IIl. y

The oscillation generator also includes means, including aconductance-controlling circuit, coupled to the oscillatory circuit 2Dfor generating oscillations therein. This means comprises an electrontube 25 which is capable of providing amplification and having the usualinput and output electrodes. The conductance-controlling cir` cuitmentioned comprises the input electrode circuit of the amplifier tube 25and is connected to the opposite ends of the oscillatory circuit 20. Theconductance-controlling circuit includes an energy-storage impedancenetwork 26, specifically a parallel-connected resistor 2l and condenser28, having a time constant longer than the time constant of damping ofthe oscillatory circuit 2li for reasons presently to be explained.Because of this long time constant, the generation of oscillations tendsto be intermittent at frequencies within at least a portion of thedesired operating frequency range of the oscillation generator I4 forreasons previously stated.

The oscillation generator I4 further includes an energizing circuit forthe amplifier tube 25 including energy-limiting and energy-storageimpedance means providing with the tube 25 a time constant shorter thanthe time constant of damping, thereby substantially to reduce thetendency of the oscillation generation of unit I4 to be intermittentover the above-mentioned portion of the frequency range of unit i4. Thisenergizing circuit includes an energy-supply means 29, such asv abattery, one terminal of which is connected to the grounded cathode ofthe amplifier tube 25 while the other terminal thereof is connected tothe anode of the tube through an energy-limiting means comprising aresistor 3B and through a feed-back winding 3l inductively coupled withthe winding ZI of the oscillatory circuit 20. The energy-storageimpedance means last mentioned comprises a condenser 32, having a Wimpedance for signals of oscillation frequency, which is coupled acrossthe series combination of the battery 29 and the resistor 30. rlheresistor 3l) preferably has a value of resistance which is greater thanthe anode-to-cathode resistance of the amplier tube 25 in itsoscillating state to provide a current-regulating action with respect tothe space-current iioW through the tube. As employed throughout thespecification and claims, the term anode-to-cathode resistance or moresimply the anode resistance of an electron tube is intended to designatethe quotient comprising the average anode-cathode voltage and theaverage space current translated by the tube. The resistor 3U and thecondenser 32 effectively provide with the anode resistance of theamplifier tube 25 a time constant which is short with respect to thetime constant of damping of the resonant circuit for stabilizing theoscillator I4 in a manner presently to be considered in greater detail.

Considering now the operation of the oscillation generator justdescribed, it will be manifest that the oscillator I 4 is of theso-called tunedgrid type wherein feedback of energy from the outputcircuit of the amplifier tube to theinput circuit thereof, to overcomelosses in the ors-,-v cillatory circuit 20, is by the inductive couplingbetween the winding 3l and the inductor 2I. As is well known, the inputelectrodes of the tube 25 introduce during a portion of each oscillationcycle a negative resistance into the oscillatory circuit 20 so tocontrol the conductance thereof as to generate oscillations. However, itwas mentioned above that the time constant of the resistor-condensernetworkr26 is longer than the time constant of damping of the `resonantcircuity 20 over the tuning range thereof. It is the purpose of thislong time constant to minimize vloading of the oscillatory circuit 20particularly at the high-frequency end of the operating range andfurther to assure good low-frequency operation. The generation ofoscillations by unit I4, Were it of conventional construction, wouldcon-v sequently tend to be intermittentat operating frequencies Withinat least a portion of thewide frequency range over which it is desiredthat the unit operate. In particular, the generation of oscillationswould ordinarily tend to be intermittent at the high-frequency portionofthe frequency range of the oscillation generator. The reasons for thishave already been mentioned. Thus, control electrode-cathode circuitstabilizal tion is ineffective over all of this desired frequency rangeof the oscillation generator I4.

Contrary to the usual procedure, effective stabilization of theoscillator I4 is procured in its energizing or anode-cathode circuit bythe deu scribed proportioning of the values of the elements thereof eventhough the parameters of the conductance-controlling circuit would seemto counteract such stabilization. The time constant of the anode-cathodecircuit may be considered to comprise the product of the capacitance ofthe condenser 32 and the effective parallel resistance of the resistor3U and the anode resistance of the tube 25. However, when the value ofthe resistor 30 is high with respect to the anode resistance of the tube25 as is desirable in most applications, for practical purposes theeffective time constant l' of the anode-cathode circuit is the productof the capacitance of the condenser 32kand `the anode resistance of thetube 25. Applicant has found that when the time constant of theanode-cath-v ode circuit of the oscillation generator is shorter thanthe time constant of damping of the oscillatory circuit 20 and the timeconstant of the conductance-controlling circuit is greater than the timeconstant of the anode-cathode circuit, that a very effective andsubstantial stabilizing action on the operation of the oscillationgenerator is provided by the anode-cathode .circuit thereof. Thus whenoscillations in the oscillatory circuit 20 begin to diminish inamplitude, less average space current flows and the anode-cathodecircuit potential quickly rises to increase the transconductance of thetube 25 and thereby increase the amplitude of oscillation to theequilibrium value. The converse action occurs upon an increase of theoscillation amplitude. This stabilization is performed at such a ratethat the resistor-condenser network 26, with its larger time constantand hence slower recovery rate, is not called upon to provide anystabilizing action. Due to the faster recovery of the anode-cathodecircuit, a negative charge of suflicient magnitude to interruptoscillations cannot be developed across the condenser 28 at anyoperating frequency within the very wide range over which the oscillatorI4 is to operate. kThe resistor 30 also assists somewhat in the anomalistabilizing actiondue to the high value of resistance thereof ascompared with that-of the other portions of the anode-cathode circuit ofthe oscillation generator i4. Thus the total effective resistance in theoutput circuit of the tube 25 is soihigh that variations of theanode-cathode resistance of the tube are relatively small in comparisontherewith. Consequently, the resistor 30 acts as a regulator which tendsto maintain the unidirectional component of current in the anodecathodecircuit of the oscillation generator substantially uniform with anychanges of the load on the generator which ordinarily may beexperienced. Therefore, the action of the energy-limiting resistor 30and 'the energizing circuit of the tube 25 with its particular timeconstant are effective to reduce, and in fact to avoid, any tendency ofthe oscillation generation of the unit I4 to be intermittent over anyportion of the relatively wide frequency range thereof despite the factvthat the conductance-controlling circuit is characterized by a very longtime constant.

While the particular form of the invention represented by Fig. 1 hasbeen described in connection with the so-calledl tuned-grid oscillationgenerator, the invention is equally useful in other types of oscillationgenerators. For example, in Fig. 2 of the drawing there is representedschematically an oscillation generator embodying the present inventionin a modified form. This oscillation generator is generally similar tothat of Fig. land corresponding circuit elements are designated by thesame reference numerals primed. In the present generator, the anode andcontrol electrode of the tube 25 are coupled to opposite ends `of theoscillatory system 2G', the control electrode being coupled to one endthereof through the coupling condenser 28 while the anode is coupled tothe other end thereof through the battery 29'. The negative terminal ofthe battery 29 is connected to the cathode of the tube through thecurrent-regulating resistor 30'. A capacitive voltage divider comprisingseries-connected condensers 35 and 30 is connected to the opposite endsof the oscillatory circuit 2D'. The resistor 21 is connected between thecontrol electrode and the cathode of the tube to provide adirect-current path therebetween. The cathode of the tube`25 isconnected to the junction of the condensers 35 and 36.

vThe resistor 2'IYand the condenser 28 comprise an energy-storageimpedance network in the conductance-controlling input circuit of theoscillation generator. These elements have a time constant which islonger than the time constant of damping of the oscillatory circuit justas in the Fig. 1 arrangement. The resistor 30', which has a high valueof resistance with respect to the anode resistance of the tube and thecondenser 3B inconjunction with the condenser 35 comprise theenergy-limiting. and the energy-storage impedance meanswhich providewith anode resistance of the tube 25 a time constant which isshorterthan the time constant of damping of the oscillatory circuit 20.Since the resistance value of the resistor is large with respect to theanode resistance of tube 25', the time constant of the energizingcircuit of the oscillation generator is effectively equal to the productof the anode resistance of tube 25' and the sum of. the capacitancevalues of the condensers and 36. Excitation voltage for theconductance-controlling input circuit is applied across the condenser 35by .theoutput circuit of tube 25. Due to the action of thecurrent-regulating resistor 30 and 0-1000 micromicrofarads 0.01microfarad Condenser 32' Condenser 28 Condenser 35 0.0012 microfaradCondenser 3B 0.006 microfarad Resistor 2l' 1.0 megohm Resistor 30 20kilohms Inductor 2| -10 microhenries to 10 millihenries Battery 29' 200volts Tube 25 Type 6J5 Frequency range 35 kilocycles-1.6 megacyclesReferring now to Fig. 3 of the drawing, there is representedschematically a further modif-ication of an oscillation generator inaccordance With the present invention. This generator is similar in manyrespects to the oscillation generator of Fig. 2 and, accordingly,corresponding elements are designated by the same reference numeralsdouble primed. The tube 25" preferably is of the pentode type ratherthan of the triode type as shown in the Fig. 2 arrangement. The anodeand the screen electrode of the tube 25 are connected to an energizingsource, indicated +B, through respective resistors 38 and 4l. The screenelectrode is also grounded through a bypass condenser 42. The suppressorelectrode is coupled to ground through a by-p-ass condenser 39 and isalso coupled to the cathode of tube 25 through a resistor 4D. Thecontrol electrode of the tube 25" is connected to a bias source,indicated +B, through the resistor 21. The resistor 21 and the condenser28" in the conductancecontrolling input circuit of the tube 25preferably have a time constant which is larger than the time constantof damping of the oscillatory circuit 20". The impedance values of theelements 2l and 28 are such that they contribute little to the loadingof the oscillatory circuit 20".

The energizing circuit of the tube 25, besides including the source +B,includes a currentregulating device preferably comprising a beamtetrodetype of electron tube 30", which tube is characterized by its very highanode-to-cathode resistance despite variations of the transconductanceof the tube. The anode of the tube 30 is connected to the cathode oftube 25" and the cathode of the former is grounded. Thus it will be seenthat the space-current path of the tube 30 is included in the cathodecircuit of the tube 25" in the same general manner as the resistor 30 ofthe Fig. 2 embodiment. Also as in the Fig. 2 arrangement, the tube 30"and the condensers 35" and 36" comprise, respectively, energy-limitingand energy-storage impedance means providing with the tube 25" a timeconstant which is shorter than the time constant of damping of theoscillatory circuit 20". The screen electrode of the tube 30 isconnected to the energizing source +B through a resistor 44 and toground through a resistor 45. The screen and control electrodes of tube3D" are coupled to ground through by-pass condensers 46 and 4l,respectively.

The oscillation generator I4 also includes means responsive to theamplitude of the oscillations generated thereby for controlling 'theenergy translated by the tube 3U and the condensers 35 and 36" tomaintain the oscillation amplitude substantially constant and, further,substantially to reduce the tendency of the oscillation generator togenerate oscillations intermittently at any frequency in the desiredfrequency range thereof. This means includes a rectifier device 50, theanode of which is connected to the anode of the tube 2'5" through acoupling condenser 48. The anode of the rectifier device 50 is connectedto the grounded cathode thereof through a load resistor 5| and is alsoconnected to the control` electrode of the tube 30" through a resistor49. Device 50 may therefore be said to be electron coupled to theoscillatory circuit through the tube 25".

Considering now the operation of the oscillation generator of Fig. 3, itwill be clear in view of the general similarity of the arrangement withthat represented in Fig. 2 that the two generators have. essentiallysimilar modes of operation. Because of the values of the time constantsof the oscillatory circuit 20" and that of the anode-cathode circuit ofthe tube and also because of the very high anode resistance aiorded bythe beam-tetrode tube any tendency of oscillation generator I4" togenerate oscillations intermittently over the entire wide frequencyrange thereof is substantially avoided. The rectifier device 50 iseiective to derive a unidirectional control eiect or potential acrossthe load resistor 5| proportional to the amplitude of the generatedoscillations, and this control po.v tential is applied as a bias to thecontrol electrode of the tube 30" through the resistor 45. This biascontrols the magnitude of the space-current flow through theseries-connected tubes 25" and 30". Should there be any tendency for theamplitude of the generated oscillations to vary for reasons such as achange in the load on the oscillation generator I4", the magnitude ofthe bias developed by the rectifier device 50 varies in the same sensewith the change in the oscillation amplitude and alters thespace-current iiow in the tube 30" accordingly. This in turn alters thespace-current now through the tube 25 and correspondingly varies thetransconductance thereof. The transconductance of tube 25 is modied inthe proper sense to return the amplitude of oscillation substantially tothe original value thereof. Thus the oscillation generator lli not onlygenerates oscillations having a substantially constant amplitude overthe entire wide operating frequency range of the generator but also isnot subject to intermittent operation over such frequency range. Oversome portions of the frequency range of the oscillator I4', it mayoperate without drawing control electrode-cathode current. This is avery unusual condition in an oscillator operating over a relatively widefrequency range. i

A similar automatic-amplification-control action may also be obtainedwhen the condenser 48 is connected to the ungrounded end of theoscillatory circuit 2U instead of to the anode of the tube 25". For someapplications, it may Drove more convenient to couple the rectiiierdevice 50 directly to the oscillatory circuit as mentioned. When this isdone, however, the rectifier device 50 applies a greater load to thetuned circuit of the oscillation generator.

` While applicant does not wish to'be limited to any particular valuesof clrcuit'constants, the

following circuit constants have proved useful in connection with anembodiment of the invention in accordance with the representation ofFig. 3:

Condenser 22" 0-0.001 microfaracl Condensers 28, 36", 39,k

and 41 0.005 microfarad 0.001 microfarad 0.05 microfarad 0.002microfarad Condenser 35" Condensers 42 and 46--.. Condenser i8 Resistors21", 40,v 49,

and5| 2 megohms Resistors 38 and 4l 20 kilohms i Resistor 45;. 10kilohmsA Inductor 2|" (individual plug-in type ele- Iime constant4ofenergizing circuit of tube 25" Time constant of damping of oscillatorycircuit 20 i Time constant ofinput circuit of tube 25" Frequency range f1l Less than 30-'1201 microseconds sii-1,000` microsecondsl 10,000microseconds kilocycles-1.6 megacycles 1 The rst value applies when alO-microhenry inductor 21 is employed and the second value pertains whena 1O0-1n1llihenryinductor is utilized.

It will be apparent from the foregoing description that an oscillationgenerator embodying the present invention, although adapted to employ inthe input circuit thereof a resistor-condenser network having a verylarge time constant, has a materially reduced tendency to generateintermittent oscillations over any portion of a relatively wide range ofoperating frequency. It will also be manifest that an oscillationgenerator in accordance with a particular form of the invention, besideshaving a reduced tendency to generateintermittent oscillations over awide frequency range, is adapted to maintain the oscillation amplitudesubstantially constant over such range.

While there have been described what are at present considered tobe the,preferred embodiments of this invention, it will be obvious to thoseskilled in the art that various` changes and modications maybe madetherein without departing from the invention, and it is, therefore,aimed to cover all such changes and modifications as fall Within thetrue spirit and scope of the in. vention.

What is claimed is:

l. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controlling circuit, coupled to said oscillatorycircuit for generating oscillations therein; saidconductance-controlling circuit including an energystorage impedancenetwork having a time constant longer thansaid time constant of dampingAso that the generation of said oscillations tends to be intermittent atfrequencies within at least a portion of said range; and an energizingcircuit for said means including energy-limiting and energy-storageimpedance means providing with said rst-mentioned means a time constantshorter than said time constant of damping substantially to reduce saidtendency of said oscillation generation to be intermittent over saidportion of said range.

2. An oscillation generator adapted for operation at any frequencywithin a relatively Wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controlling circuit, coupled to said oscillatorycircuit for generating oscillations therein; saidconductance-controlling circuit including an energystorage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations is intermittentfatfrequencies within at least a portion of said range; and an energizingcircuit for said means including energy-limiting and energy-storageimpedance means providing with said first-mentioned means a timeconstant shorter than said time constant of damping so that saidintermittent oscillation generation is avoided over said portion of saidrange.

3. An oscillation generator adapted for operation at any frequencyWithin a relatively Wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controlling circuit, counled to said oscillatorycircuit for generating oscillations therein; saidconductance-controlling circuit including an energystorage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations tends to be intermittent atthe high-frequency portion of said range; and an energizing circuit forsaid means including energy-limiting and energystorage impedance meansproviding with said first-mentioned means a time constant shorter thansaid time constant of damping substantially to reduce said tendency ofsaid oscillation generation to be intermittent over said high-frequencyportion of said range.

4. An oscillation generator adapted for operation at any frequencyWithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damning; means,including a conductance-controlling circuit, coupled to said oscillatorycircuit for generating oscillations therein; saidconductance-controlling circuit including an energystorage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations tends to be intermittent atfrequencies within at least a portion of said range; and an energizingcircuit for said means including a constant-current device and anenergy-storage impedance means providing with said first-mentioned meansa time constant shorter than said time constant of damping substantiallyto reduce said tendency of said oscillation generation to beintermittent over said portion of said range.

5. An oscillation generator adapted for operation at any frequencywithin a relatively Wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controlling circuit, coupled to said oscillatorycircuit for generating oscillations therein; saidconductance-controlling circuit including an energystorage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations tends to be intermittent atfrequencies within at least a portion of said range; and an energizingcircuit for said means including a constant-current electron tube and anenergy-storage impedance means providing with said inst-mentioned meansa time constant shorter than said time constant of damping substantiallyto reduce said tendency of said oscillation generation to beintermittent over said portion of said range.

6. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; an electrontube, including a conductance-controlling circuit, coupled to saidoscillatory circuit for generating' oscillations therein; saidconductance-controlling circuit including an energy-storage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations tends to be intermittent atfrequencies Within at least a portion of said range; and an energizingcircuit for said tube including energy-limiting and energy-storageimpedance means providing with the anode resistance of said tube a timeconstant shorter than said time constant of damping substantially toreduce said tendency of said oscillation generation to be intermittentover said portion of said range.

7. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; an electrontube, including a conductance-controlling circuit, coupled to saidoscilla.- tory circuit for generating oscillations therein; saidconductance-controlling circuit including an energy-storage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations tends to be intermittent atfrequencies Within at east a portion of said range; and an energizingcircuit for said tube including a condenser and a current-regulatingelectron tube providing with the anode resistance of said rst-mentionedtube a time constant shorter than said time constant of dampingsubstantially to reduce said tendency of said oscillation generation tobe intermittent over said portion of said range.

8. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; an electrontube, including a conductance-controlling circuit, coupled to saidoscillatory circuit for generatingl oscillations therein; saidconductance-controlling circuit including an energy-storage impedancenetwork having a time constant longer than said time constant cf dampingso that the generation of said oscillations tends to be intermittent atfrequencies Within at least a portion of said range; and an energizingcircuit for said tube including a condenser and a .current-regulatingelectron tube having a high anode resistance providing with the anoderesistance of said first-mentioned tube a time constant shorter thansaid time constant of damping substantially to reduce said tendency ofsaid oscillation generation to be intermittent over said portion of saidrange.v

9. An oscillation generator adapted for operation at any frequencywithin a relatively Wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; an electrontube, including a conductance-controlling circuit, coupled to saidoscillatory circuit for generating oscillations therein; saidconductance-controlling circuit including an energy-storage impedancenetwork having a time constant longer than said time constant of dampingso that the generation of said oscillations tends to be intermittent atfrequencies within at least a portion of said range; and an energizingcircuit for said tube including a condenser a-nd a resistor having ahigh value of resistance with reference to the anode resistance of saidtube and providing with said anode resistance a time constant shorterthan said time constant of damping substantially to reduce saidtendencyT of said oscillation generation to be intermittent over saidoperation vof said range.

10. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controlling circuit, coupled to said oscillatorycircuit for generating oscillations therein; said conductancecontrolling circuit including an energystorage impedance network havinga time constance longer than said time constant of damping so that saidgeneration of said oscillations tends to become intermittent atfrequencies Within at least a portion of said range; an energizingcircuit for said means including energylimiting and energy-storageimpedance means providing with said first-mentioned means a timeconstant shorter than said time constant of damping; and means includinga rectier devicel coupled to said oscillatory circuit and responsive tothe amplitude of said generated oscillations for controlling the energytranslated by said energy-limiting and energy-storage impedance means tomaintain said oscillation ampltiude substantially constant andsubstantially to reduce any tendency of said generator to generateoscillations intermittently at any frequency in said range.

l1. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controlling circuit, coupled to said oscillatorycircuit for generating oscillations therein; saidconductance-controlling circuit including an energystorage impedancenetwork having a time constant longer than said time constant of dampingso that said generation of said oscillations tends to be intermittent atfrequencies within at least a portion of said range; an energizingcircuit for said means including energy-limiting and' energy-storageimpedance means providing With said first-mentioned means a timeconstant shorter than said time -constant of damping; and meansresponsive to the amplitude of said generated oscillations forcontrolling the energy translated by said energy-limiting andenergystorage impedance means to maintain said oscillation amplitudesubstantially constant and substantially to reduce said tendency of saidgenerator to generate oscillations intermittently over said portion ofsaid range.

l2. An oscillation generator adapted for operation at any frequencyWithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; an amplier tubehaving input and output electrodes including an anode electrode; aninput circuit and an output circuit respectively coupling said input andoutput electrodes with said oscillatory circuit for controlling theconductance thereof to develop oscillations therein; said input circuitincluding an energy-storage impedance network having a time constantwhich is longer than said time vconstant of damping so that thegeneration of said oscillations tends to be intermittent at frequencieswithin'a portion of said range; and said output circuit includingenergy-supply means, energy-limiting means having a value of resistancegreater than the anode resistance of lsaid tube, and an energystorageimpedance means, said three means providing with said anode resistanceof said tube a timeconstant shorter than said time constant of dampingsubstantially to reduce said tendency of said oscillation generation tobe intermittent over said portion of said range.

13. An oscillation generator adapted for operation at any frequency`within a relatively Wide range of frequencies comprising: anoscillatory circuit having a predetermined time constant of damping; anamplifier tube having input and output electrodes including an anodeelectrode; anv

input circuit and an output circuit respectively coupling said input andoutput electrodes with said oscillatory circuit for controlling theconductance thereof to develop oscillations therein; said input circuitincluding a resistor-condenser network having a time constant which islonger than said time constant of damping so that the generation of saidoscillations tends to be intermittent at frequencies within a portion ofsaid range; and said output circuit including energysupply means, meansfor maintaining the space current of said amplifier tube within arelatively narrow range of values and having a value of resistancegreater than the anode resistance of said tube, and an energy-storageimpedance means, said three means providing with said anode resistanceof said tube a time constant shorter than said time constant of dampingsubstantially to reduce said tendency of said oscillation generation tobe intermittent over said portion of said range.

14. An oscillation generator adapted for operation at any frequencywithin a relatively wide range of frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; a rst amplifiertube having input and output electrodes including an anode electrode; aninput circuit and an output circuit respectively coupling said input andoutput electrodes with said oscillatory circuit for controlling theconductance thereof to develop oscillations therein; said input circuitincluding an energy-storage impedance network having a time constantwhich is longer than said timeconstant of damping so that the generationof said oscillations tends to be intermittent at frequencies within aportion of said range; and said output circuit including energy-supplymeans, a second amplifier tube having an anode resistance at leastcomparable with the anode resistance of said rst tube, and anenergy-storage impedance means, said two means providing with said anoderesistances of said rst and second tubes a time constant shorter thansaid time constant of damping substantially to reduce said tendency 0fsaid oscillation generation 'to be intermittent over4 said portion ofsaidrange.

15. An. oscillation generator adapted for operationz at any frequencyWithin a relatively wide rangeof frequencies comprising: an oscillatorycircuit having a predetermined time constant of damping; means,including a conductance-controllingcircuit, coupled to said oscillatorycircuit forgenerating oscillations therein; said conductance controllingcircuit including an energy-storage'impedance network having a timeconstant longer .than said time constant of damping so that saidIgeneration of said oscillations tends to become-intermittent atfrequencies Within at least a portionofsaid range;A an energizingcircuitfor saidmeansincluding a series-connected amplifier .tube and ashunt-connected condenser providing with `said Erst-mentioned means atime constant shorter than said time constant of damping; and meansincluding a rectier device coupled to said oscillatoryrcircuit forderiving a controlr effect proportional to the amplitude of 16saidogenerated .oscillations andfor applying said controlt effect tosaid'amplier tube to vary the transconductance thereof in accordancetherewith, thereby to maintain said oscillation amplitude substantiallyconstant and substantially to reduce any tendency of said generator togenerate oscillations intermittently at any frequency in said range.

HAROLD A. WHEELER.

REFERENCES CITED The following :references are of record in the le ofthistpatent:

UNTTED STATES PATENTS Number Name Date 2,294,171' George Aug. 25, 19422,355,606 Shannonl Aug. 15, 1944 OTHER REFERENCES ARRL Handbook, 1942edition, page 126, FigureV

